Typically, a power module is primarily configured by a power semiconductor mounting substrate on which is mounted a chip such as a power semiconductor whose heat emission is relatively large, a non-power semiconductor mounting substrate on which is mounted an IC chip such as a microcomputer whose heat emission is relatively small, and a cooling unit (e.g., a heat dissipating fin, etc.) for cooling primarily the power semiconductor (e.g., see JP-A No. 2004-111619).